cr250rgio

Hey everyone

So im having some weird issues. I have a 91 4x4 ex cab toyota pickup with the 3.slo and a 5 speed. Whats happening is that if it has been sitting for 10 min or longer and i go to start it up the motor sound really good and powerful. Then about 5 seconds after its been started its like something switches over and when it revs between 3000 and 4000 rpms it has a weird mmmmm sound and it doesnt sound to powerful. At this point it will almost struggle to get past 4000 rps

The truck just got a new maf sensor and a new O2 sensor.

Just wanted to know what you guys would think of this. Any responses would be great

thanks, Gio